 Data storage is the recording sporing of information data in a storage medium. DNA and RNA, hand writing, phonographic recording, magnetic tape, and optical disks are all examples of storage media. Recording is accomplished by virtually any form of energy. Electronic data storage requires electrical power to store and retrieve data. Data storage in a digital, machine-readable medium is sometimes called digital data. Computer data storage is one of the core functions of a general-purpose computer. Electronic documents can be stored in much less space than paper documents. Barcodes and magnetic ink character recognition and ICR are two ways of recording machine-readable data on paper.